Under the starry night, Subaru, armed with a telescope, heads to her school's observatory to witness a meteor shower. To her surprise, instead of the expected celestial display, she stumbles upon a secret garden behind the door, adorned with a dazzling fountain and a mysterious boy with crimson hair. The enchanting garden vanishes swiftly, leaving behind a peculiar bouncing creature that guides Subaru to a magical door where girls in witch-like attire await. Revelations unfold rapidly: her childhood friend Aoi is among them, the bouncing creature is an alien named Pleiadian seeking to journey home, and Subaru is chosen to join their mystical group. With this unexpected turn of events, Subaru's stellar aspirations materialize in a fantastical manner as she and her companions strive to retrieve fragments of the Pleiadian spacecraft engine for its return journey. However, they face competition in this quest, their adversaries' motives shrouded in mystery.